Daily intakes of more than 100 ml of tea or coffee may significantly reduce the risk of certain brain tumors, according to new research published in the American Journal of Clinical Nutrition.
The study is based on data from over half a million people in the European Prospective Investigation into Cancer and Nutrition (EPIC) study, and finds that people consuming over 100 ml of tea, coffee, or both, per day are at significantly lower risk of glioblastoma tumours (glioma) than those consuming less than 100 ml per day.
“In this large cohort study, we observed an inverse association between total coffee and tea consumption and risk of glioma,” wrote the researchers, led by Dr. Dominique S Michaud from the Department of Epidemiology and Public Health at Imperial College, London.
According to the American Brain Tumor Association, glioma's are tumors that start in the supportive tissue brain. The exact causes of gliomas are not known, however the prognosis for people once diagnosed with the type of tumour is usually very poor.
A recent US study found total coffee and tea consumption was inversely associated with risk of glioma, whilst experimental studies have shown caffeine can slow the invasive growth of glioblastoma tumours.
However very few large scale epidemiologic studies have measured the association between coffee, tea, or caffeinated beverages and glioma risk. The authors noted that the results of these studies “have been inconsistent”.
“Given the limited evidence suggesting that coffee and tea intake may reduce the risk of glioma, more studies are needed to address this hypothesis,” stated the researchers.
In the new study, the researchers examined the relation between coffee and tea intake and risk of glioma and meningioma.
A significant inverse association was observed for glioma risk when consuming more than 100 ml coffee and tea per day, compared consuming less than 100 ml per day.
However, the researchers observed no association between coffee, tea, or combined coffee and tea consumption and risk of either type of brain tumor when looking at data based on country-specific intakes.
No association was reported for meningioma risk with the same intake values for coffee and tea intake combined, or when a higher cutoff of 200 ml per day was used.
“Given that we did not observe an association between coffee and tea consumption and meningioma risk, it is possible that the effect of coffee, if causal, is acting late in the process of carcinogenesis by preventing tumor growth,” suggested the researchers.
Another potential mechanism that may be implicated in the observed effects, involves the DNA repair protein MGMT. Higher activation of MGMT is believed to have a protective effect against development of several types of cancer, including colon cancer and glioma.
Coffee compounds kahweol and cafestol have been reported to increase MGMT activity in rats, whilst certain tea polyphenols are known to reactivate genes in cancer cells – including MGMT.
“These findings, if further replicated in other studies, may provide new avenues of research on gliomas,” they added.
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi:
“Coffee and tea intake and risk of brain tumors in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study”
Authors: D.S Michaud, V. Gallo, B. Schlehofer, A. Tjønneland, A. Olsen, K. Overvad, et al.